Question

what is 'depletion of ozone layer'? How is it caused

Answer 1

Depletion of ozone mean that the ozone layer is now getting finish.
It is caused by air releasing by ACs, fridge etc.

Answer 2

The ozone layer is a thin layer in the atmosphere that has a high concentration of ozone gas. It is made up of three atoms of oxygen. Ozone layer absorb the UV rays from the sun and prevent it from reaching the earth’s surface. The ozone layer is not uniform throughout the earth; it is thick at some places and thin at others. If this layer becomes too thin, it cannot stop the UV rays from entering the earth. The process in which the ozone layer is becoming thinner day by day is depletion of ozone layer.
The major cause of the thinning of the ozone layer is the use of chloro-fluoro-carbons or CFCs and Hydro- Chloro-fluoro-carbons or HCFCs.These are used as refrigerants in refrigerators, ACs, and cooling plants. These molecules can destroy O3 molecules and hence make the O3 layer thinner.